Electromagnet



, is ineffective.

GEORGE C. CUMMINGS, OF EAST ORANGE, .NE-W JERSEY.

ELECTROMAGNET.

Specication of Letters Patent.

Patented Mar. 9, 1920.

Application ,led May 1, 1919. Serial No. 294,117.

To all whom it may Concern.'

Be it known that I, GEORGE C. CUMMINGS, subject of King George ofEngland, residing at East Orange, in the county of Essex and State ofNew Jersey, have invented a certain new and useful Improvement inElectromagnets, of which the followingV is a full, clear, concise, andexact description.

My invention, in one aspect, relatesto electromagnets included in theclass that embraces the polarized relay disclosed in the expired patentto Anderson, 267,966, of November'21, 1882.

The invention also relates to a novel armature mounting 4 which ispreferably employed in the vmagnet having the other characteristics ofmy invention.

The invention has for one of its objects the elimination of residualmagnetism in the oscillating relay or magnet armature that is arrangedalong a face of a polar end of the magnet. In carrying out my inventionthis polar face is of a length that is a multiple of twice the width ofthe space between the axis of the armature and said Vpolar face. Thisarmature is threaded transversely ofits length by the flux of a magnet,

preferably a permanent magnet, substantially throughout all of thearmature that is opposite said .polar face. The armature is operable bymeans of an energizing circuit that includes a winding arranged, whenthe circuit is effective, to set up flux in said armature longitudinallythereof, the transverse flux of the aforesaid permanent magnet being ofstrength effective to eliminate longitudinal flux or residual magnetismin said armature when said energizing circuit In' the preferredembodiment of the invention thev magnet that establishes the transversefluir' has closely approached polar ends whose opposing faces aresubstantially parallel throughout a length that is a multiple of thewidth of the space between said parallel faces.

In magnets of the prior art the interpolar spaces were very wide andshort. The flux produced by the permanent magnts'of the prior art wouldnot be permitted to exceed the most favorable magnetization points toprevent the magnets from becoming insensitive, a result that wouldfollow excessive iluX due to increased pressure of the Varmavoperatingflux before effecting armature movement. The limitations heretoforepresent in the design of such magnets or relays have made it impossibleto produce structures in which the permanent magnets would eliminate theresidual magnetism, owing to the fact that only small portions of thearmature lengths were subject to the transverse fiuXof the permanentmagnets. When there is residual magnetism in the armature a forcesubstantially equal thereto must be dded to the forceexerted by theoperating In accordance with the remaining feature of my invention thearmature is mounted upon a bar spring with which the armature is inrigid connection. This bar spring is preferably a strip metal springsecured at its ends to a suitable support.y By means of such an armaturemounting the armature may be held in mid position without engagementwith either front or back contact.

I will explain my invention more fully by reference to the accompanying`drawing showing the preferred embodiment thereof and in which Figure 1is a view, somewhat diagrammatic, illustrating the preferred structureof my invention; Fig. 2 vis a perspective view of a structure embracingthe invention, parts being indicated in section; and Fig. 3 is aperspective view illustrating the preferred armature mounting.

Like parts are indicated by similar characters of reference throughoutthe different figures.

The magnet which I employ for effecting the transverse flux is desirablypermanent and is preferably made up of a number of horseshoe magnetelements lhaving closely approached polar ends 2 and 3. The polar ends 2of the magnet elements 1 are upon one side of the interpolar gap and thepolar v stops.

ends 3 of the magnet elements l are upon the other 'side of theinterpolar gap. The opposing faces of the polar ends of the com-- poundmagnetV are substantially parallel throughout a length that is amultiple of the width of the space between said parallel faces. Anoscillating armature 4 is located in and is disposed longitudinally ofvsaid space and is threaded transversely of its length by the -fluxofthe permanent magnet y substantially'throughout all of the armaturethat is in said space, An energizing circuit is provided for` thearmature and includes a winding 5V arranged, when the circuit iseffective, to set up flux in the armature longitudinally thereof, thetransverse flux of f the compound magnet being of strength effective toeliminate longitudinal fluX or residual magnetism in said armaturewhensaid energizing circuit is ineffective. The mounting for theswinging armature/is desirably inthe form of a bar spring 6 which ispreferably a strip metal spring permitting slight axial movement of thearmature. This slight axial movement is the reciprocatinglengthwisemovement of the armature at the contact points where the structure'isused for a relay. The armature is brought into rigid relation with saidspring where connected therewith by means of a pin 7 i rigidly securedto the armature and spring. The armature supporting spring is itselfsupported at its ends upon the nonmagnetic support 8. The pin 7 is astrain equalizing pin that serves to distribute' the torque of thespring evenly across the face of such spring which may be so arrangedthat its force is always such as to maintain or tend to maintain thearmature in the center of the space between the contact 'screws or stops9 and 10.- Such spring force is adjusted so as nearly to but not quiteoffset the force, due to the permanent magnet flux,

that tends to hold the armature against said The armature is positionedto be subject to the actuating influence of the flux 'on both sides ofthe spring.

It will be observed that each polar end face of the permanent magnet isof a length that is a multiple of twice the width of the space betweenthe axis of the armature and said face and while I prefer to employ twoclosely approached polar ends, I do not wish to be limited to thisarrangement. It is preferable to make the width between the pole facescommensurate with the height of each individual one of the severalpermanent magnets comprising the structure because thereby thereluctance of the air gap between the faces insures a considerablepercentage of the iux established by the permanent magnet passingdirectly across this `gap rather than taking the longer and greaterreluctance path out to the added tween the pole faces at all points. Thetwo' together insure that the transverse flux shall be effective toeliminate residual magnetism.

In a very effective arrangement the distance between t-he poles is notmore than onesixth of the length of each polar'face, such length beingmeasured along the armature,

and the strength of the permanent magnet should be ten or fifteen timesthat which is ordinarily present in a relay structure of the aforesaidAnderson type. By the arrangement herein disclosed an intensesubstantially equally distributed transverse field is established,neglecting reference to the leakage -and fringe effects over the facesof the poles.

The armature 4 may be of soft iron, if desired, and preferably has anon-magnetic continuation 11 to carry contacts 12-and 13 when thestructure is employed as a relay. The intense transverse magnetic fielddue to the combined permanent magnet effects the arrangement of themolecules of the armature in alinement with each other in the transversedirections followed by the permanent magnet flux whereby one long faceof thearniature is caused to be of one polarity and the face of thearmature parallel to the aforesaid armature face is caused to be of theopposite polarity.

The operating circuit of the magnet is inclusive of a winding 5 which ispreferably subdivided into two coils arranged on opposite sides of thearmature mounting spring 6. Any suitable form of circuit controllingswitch is employed, a circuit closing switch tion. This iux will causethe movement of the armature in one direction or the other dependingupon the polarity of the battery and the direction of the winding 5.When the key 14 is released so as tobe in open position ther moleculesof the armature which were disturbed by the longitudinal flux willassume their former positions transverse of the armature and parallelwith the transverse flux of the permanent magnet which is at rightangles to the length of the armature, such a shifting of the disturbedmolecules to normal position being due to the intensity of thetransverse flux ofthe permanent magnet. All longitudinal flux, orresidual magnetism, in the armature is thus eifaced when the operatingcircuit of the ma net is opened.

n thepreferred embodiment of the invention illustrated in Fig. 2 thereare em-l ployed miniature polar extensions 16 that serve merely toconcentrate locally very small portions of thev transverse permanentmagnet flux adjacent the ends of the armature to correspond with theconcentration of the operating flux at thearmature extremities. i

In the structure of the Anderson type the forces which tend to move thearmature and that result from the operating current fluxv are thoseexerted within the limitations of the polar extensions adjacent theextremities 'of the; armature.` In my structure the forces tending tomove the armature are not only existent within Ithe limits of the polarextensions 16- but are'strongly existent over the maj or portion of thelength of the armature because of the tendency of the transversepermanent magnet field that suppliesr a field of flux overthe entirelength of the armature to enable 'the lweaker operating flux to becomeeffective to move the armature, this weaker operating flux being effec?tive throughout the major portion of the armature length` as well as atthe armature extremities.

While I have herein shown and particu'- larly described the preferredembodiment of v my invention I do not wish to be limited to the precisedetails of construction shown as 'changes may readily be made withoutdeparting from the spirit of my invention, but having thus described myinvention I claim as new and desire to secure by Letters Pat- 1. Amagnet structure including a permanent magnet having closely approachedpolar ends whose;4 opposing faces are sub' stantially parallelthroughout`a length that f is a multiple of the width of the space be--tween said parallel faces; an oscillating i armature inv anddisposedlongitudinally of said space and threaded transversely of itslength by the flux of the permanent magnet substantially throughout allof the armature that is in said space; and an energizing cirrcuit forsaid armature including a winding arranged, when the circuit is eective,to set up iux in saidv armature longitudinally thereof, the transverseHux ofthe permanent magnet being of strength e`ective to eliminatelongitudinal flux or residual magnetism in said armature when saidenergiz-y ing circuitis ineffective. .A

2. A. magnet structure including a magnet having closely 'approached`polar ends whose opposing faces are substantially parallel throughout .alength that is a multiple of the widthAv of the space between `said Iparallel faces; an oscillating armature in and disposed longitudinallyof said space and threaded transversely of its length by the flux of themagnet substantially throughout all of Ythe armature that. is in saidspace; and an energizing circuit for said armature including a windingarranged, when the circuit is effective, to set up flux in said armaturelon itudinally thereof, the transverse flux of tIie magnet being ofstrength effective to eliminate longitudinal flux or residual ma etismin said armature when said energizing circuit is ineffective.

3. Amagnet structure including a permanent magnet; an oscillatingarmature arranged along a face'of a polar end of said magnet, which faceis of a length that isl a multiple of twice the width of the spacebetween the axis of the armature and said face, said armature beingthreaded-transversely of its length by the flux of the permanent magnetsubstantially throughout all of the armature that is'l opposite said-polar face; and an energizing circuit for said armature including awinding arranged, when the' circuit is effective to set up flux in saidarmature longitudina ly thereof, the transverse flux of the permanentmagnet being of strength effective to eliminate longi tudinal flux orresidual magnetism in'said armature when said energizing circuit is ineffective.

4. A ma net structure including a-.Imagnet; an oscillating armaturearranged along.

twice the width of the space between the axis of the armature andsaidface, said armature being threaded transversely of its length by theflux of the magnet substantially throughout all of the armature that isopposite said polar face; and an energizing circuit for said armatureincluding a winding arranged, when the circuit/is effective, to setupflux in said armature longitudinall thereof, `the transverse flux ofthe magnet eing of strength effective to eliminate longitudinal flux4 orresidual magnetism in said armature when said energizing circuit isinefective. p

5. An electro-magnet including a magnet winding; a swinging armaturemovable by the flux due to said winding; a bar spring extendingtransversely of the armature and upon an intermediate portion of whichthe armature is mounted at an intermediate portion of the armature wherethe armature is in rigid connection with the spring, the armature beingpositioned to be subject to the actuating iniiuence of the flux on both-sides of said spring; and a support for ,holding the ends of saidspring in fixed relation. 6. An electro-magnet including a magnetwinding; a swinging armature movable by lll@ the flux due to saidWinding; a bei' spring extending transversely of the armatui'efand uponan intermediate portion of which the arma-ture is mounted atal1-intermediate portion of the armature Where theJ armaturelis in rigidconnection with: the spring, the armature being positioned 'be subjectto the actuating influence of the iux on both sides of said spring; anda support for said spring. `.10 In witness whereof, hereunto subscribe

